Aqueous Co‐Solvent in Zwitterionic‐based Protic Ionic Liquids as Electrolytes in 2.0 V Supercapacitors

Abstract

High-performance energy-storage devices are receiving great interest in sustainable terms as a required complement to renewable energy sources to level out the imbalances between supply and demand. Besides electrode optimization, a primary objective is also the judicious design of high-performance electrolytes combining novel ionic liquids (ILs) and mixtures of aqueous solvents capable of offering "à la carte" properties. Herein, it is described the stoichiometric addition of a zwitterion such as betaine (BET) to protic ILs (PILs) such as those formed between methane sulfonic acid (MSAH) or p-toluenesulfonic acid (PTSAH) with ethanolamine (EOA). This addition resulted in the formation of zwitterionic-based PILs (ZPILs) containing the original anion and cation as well as the zwitterion. The ZPILs prepared in this work ([EOAH] + [BET][MSA] À and [EOAH] + [BET] [PTSA] À) were liquid at room temperature even though the original PILs ([EOAH] + [MSA] À and [EOAH] + [PTSA] À) were not. Moreover, ZPILs exhibited a wide electrochemical stability window, up to 3.7 V vs. Ag wire for [EOAH] + [BET][MSA] À and 4.0 V vs. Ag wire for [EOAH] + [BET][PTSA] À at room temperature, and a high miscibility with both water and aqueous co-solvent (WcS) mixtures. In particular, "WcS-in-ZPIL" mixtures of [EOAH] + [BET][MSA] À in 2 H 2 O/ACN/DMSO provided specific capacitances of approximately 83 F g À 1 at current densities of 1 A g À 1 , and capacity retentions of approximately 90 % after 6000 cycles when operating at a voltage of 2.0 V and a current density of 4 A g À 1 .

Implications for new particle formation in air of the use of monoethanolamine in carbon capture and storage

“…156 Furthermore, MEA-MSA has been reported to have properties of a protic ionic liquid, even though it remains a solid at room temperature. [156][157][158][159] Its properties include a glass transition of À44 1C, melting point of about 100 1C, and a thermal stability up to 286-323 1C for the fused salt. 156 Tropospheric air contains significant amounts of water vapor, hence the impact of relative humidity (RH) on particle formation from MEA + MSA was also examined.…”

“…156 Furthermore, MEA–MSA has been reported to have properties of a protic ionic liquid, even though it remains a solid at room temperature. 156–159 Its properties include a glass transition of −44 °C, melting point of about 100 °C, and a thermal stability up to 286–323 °C for the fused salt. 156…”

Ultra‐stable Zinc Metal Anodes at −20 °C through Eutectic Solvation Sheath in Chlorine‐functionalized Eutectic Electrolytes with 1,3‐Dioxolane

“…As a result, Cl-functionalized eutectics take advantage of hydrogen atoms' participation domaining from H 2 O to construct strong H-bonding structures with Cl À and OAc À , representing a deshielding effect with the subsequent depletion of electronic density around hydrogen atoms. [32] DOL as an additive in ether-based electrolytes was intensively exploited considering its high stability against the reduction, low freezing point (À 95 °C), and tender collaboration with other co-solvents (e.g., DME and water) for lithium-ion batteries (LIBs), [33] sodium-ion batteries (SIBs), [34] and beyond, achieving a wide ESW and simultaneously maintaining fast ion transport at sub-zero temperatures. [35] Meanwhile, it would be interesting to investigate the eutectic-DOL interaction strength and collaboration pattern in terms of the Zn-ion storage capacity at ZIHC scenarios in a full cell configuration (Zn as anodes and activated carbon (AC) as cathodes).…”

Ionic Liquids for Supercapacitive Energy Storage: A Mini-Review

“…The modification of IL electrolytes with other ILs, conductive salts, and nonaqueous solvents has lately been at the forefront of active research to ameliorate the relatively high viscosity and unsatisfactory conductivity for neat ILs ( e.g. , 0.014 S cm –1 at 25 °C for EMIMBF 4 ). − Strong cation–anion attraction in neat ILs confines the mobility of ions, leading to sluggish ion-transfer dynamics in viscous media . For instance, He’s group performed molecular dynamics simulations to investigate the correlation between anion types and electrochemical performances for IL-based supercapacitors; consequently, both double-layer thickness and charging time increased by the anion diameter BF 4 – < PF 6 – < OTf – < TFSI – , which also indicated the restrained ion migration owing to the large anion diameter .…”